Wednesday, December 14, 2016

Sex-Specific Virulence in HTLV-1

Though not
common knowledge, infectious diseases often prove more fatal in men than in
women. In the past, this difference has been attributed to women having more robust
immune responses, but a recently published article in Nature Communications may prove otherwise. Researchers Francisco
Ubeda and Vincent Jansen, of Royal Holloway, University of London, studied the
progression of Human T-cell Lymphotropic Virus I (HTLV-1) into adult T-cell
leukemia, in Japanese and Caribbean cohorts to try and learn more about these sexually-based differences. In the Japanese group, the progression occurs 2 to 3.5 times more frequently
in men, while the progression occurs at an equal rate within the Caribbean cohort.
The team has proposed that cultural differences in breast feeding may help to
explain the discrepancy between the two groups.

HTLV-1 is a
virus transmitted through sexual contact and breastfeeding. In
Japan, mothers breast feed their children for longer durations, and in larger quantities
than Caribbean women do. Ubeda and Jansen argue that the virus has developed a
lower virulence within Japanese women relative to Caribbean women, due to its increased vertical transmission rate in the Japanese group (due to the increased duration and frequencies of breastfeeding in the Japanese group). To back their hypothesis,
the team developed a mathematical model, which did show increased selection for
viruses with differing mortalities between sexes, for viruses transmitted both
horizontally and vertically. Ubeda and Jansen hope that this work helps lead to more effective, sex specific treatments for HTLV-1, and other viruses
with sex-specific virulences.